Into the Darkness of my Mind
by HollyeLeigh
Summary: CS Post S7 Canon Compliant(ish): Killian knew of the origins of Halloween, the belief many held about the veil between worlds being thin enough for the dead to pass over into the land of the living. Never did he imagine that such a phenomena would actually occur, or that he would be the one responsible for allowing an old, formidable foe return from the bowels of the Underworld.


_**Part of the CS Role Reversal event on Tumblr. This fic is inspired by a dream cocohook38 had. I told her if she drew, I'd write it, and here we are. **_

_**Post S7, mostly canon compliant fic. However, I am not using the concept of the United Realms. My head canon is that traveling between worlds is much easier than it used to be, with scheduled portals opening at certain places at certain times. Like catching the bus or train.**_

* * *

**Part One**

Killian sat with his arm wrapped around his Swan as they sat upon a bench overlooking Storybrooke pond with the sound of children's laughter wisping through the breeze from Main Street. The crisp autumn air fluttered through his hair and rippled over the surface of the water, the stinging bite of brine from the nearby ocean scratching through his sinuses and down his throat with each deep inhale as he enjoyed the contented calm this spot afforded them.

Unlike the chaos currently running rampant in the town square with its vendor booths and games dedicated to all things macabre as the denizens celebrated another of this realm's traditions.

It still struck Killian as an oddity that a town created by magic and surrounded by its craftings day in and day out would throw itself so fully into the customs of what this land referred to as _Halloween_. The town had always been magical, with witches and spells, enchantments and supernatural beasts, portals to other realms, and fairytale creatures come to life, but something about the fall, and the holiday currently running amok throughout their little hamlet, only seemed to enhance those qualities.

Indeed, this time of year seemed to cast a mystical glow upon the entire Land Without Magic. The tranquility of the season as it prepared the land and sea for a long winter's sleep, likened itself to the rhythm of a bedtime routine. The dimming of the world, its darkening blanket rolled out earlier and earlier each night as the sun disappeared behind the horizon was similar to the way Emma wandered through their home, turning out lights as the evening wound down; the chill of the air, reminiscent of Hope's little tremble when she emerged from her bath, her father quick to wrap a plush towel around his little love to ward off the cold. Killian couldn't deny that even in the various realms he'd encountered over the years there was something about the fall that held an intrigue and mystery. A sense of anticipation, sometimes laced with foreboding, such as a child might feel as they lay awake beneath their covers and contemplate what might be lurking under their bed or behind the closet door.

Killian frowned a bit at the thought. He could foresee a long night of _checking for monsters _in Hope's room once they got her home, so he should probably enjoy the solace he and Emma were presently experiencing while it lasted. Not that he hadn't loved every moment of his daughter's squeals and giggles as they wandered down Main Street, collecting candy from the various businesses before arriving at the carnival in the square. Hope's enthusiasm (_and mounting sugar rush_) had pulled a number of chuckles and smiles from both him and Emma, but when Henry had offered to take charge of his little sister for a bit so his mother and step-father could go and enjoy some of the more adult offerings of the event, they hadn't needed him to offer twice. With spiked ciders in hand, they'd watched Hope toddle off, hand-in-hand with Lucy, as Henry, Jacinda, Alice, and Robin followed in their wake before making their way off the square to the secluded area by the pond.

Now a spot where they came to find respite, it had taken some time over the years for both him and Emma to find peace beside the pond, given the memories it held. To this day Killian couldn't help but shudder whenever his eyes landed on the patch of ground once soaked with his own blood after he'd collapsed in Emma's arms after she'd lanced the Darkness out of them. His turmoil born of a mix between the shame of what he'd nearly done to Emma and her family - _his family _\- and the allusion of Excalibur slicing through his abdomen, which he could still feel after all this time.

The memories were nothing more than ghosts now, but he knew they still haunted his Swan from time to time as well. Their specters seemed more prevalent this evening, but Killian shrugged them off as nothing more than overactive synapses of his mind, stirred up by the eerie atmosphere of the holiday, choosing instead to focus on the tranquility of the chilly evening and the warmth of the woman he loved pressed into his side.

Leaves rustled in the trees overhead, a few no longer able to keep their tether, their gentle descent landing them on the black waters of the pond. Killian watched the newest of the fallen, its bright yellow and orange color no less vivid in the encroaching blackness creeping over them now that the sun had fully set. It swiveled and danced, guided by the gentle ripples, until it came to rest nestled among others that had already fallen, the waning foliage creating a quilt of autumn colors along the shoreline.

"How much longer should we give them?" Emma inquired softly. Her gaze was stretched out across the pond, a restful expression lazing upon her features, one hand loosely holding her now empty cider cup while the other mindlessly caressed his thigh. He was loathe to bring the moment to an end, but they both knew Hope's bedtime was rapidly approaching.

"A bit longer, love," Killian replied, greedy to be alone with his Swan for just a few minutes more. Despite the distinct lack of any villainy endangering the town in recent years, quiet moments were still at a premium, what with their even greater expanded family and their own little one to keep them busy. So, sue him if he wanted to pirate himself and his wife away from responsibility a little while longer.

"Okay," she agreed, snuggling further into his side, "but not too much longer, not with the veil so thin tonight. You never know what horrors might come lurking." Her tone had taken on the teasing quality Henry liked to call _spooky, _while her brows waggled up at him.

Killian chuckled. She had told him about the holiday's origins, the belief many held about the veil between worlds being thin enough for the dead to pass over into the land of the living. He shook his head at her and tightened his braced arm around her shoulder, a shiver running down his back from a fresh breeze blowing across the water.

Emma trembled at it, too. Not one to enjoy the cold, she sighed and relented, "I guess we should go find them and get Hope home. Hand me your cup and I'll toss them in the bin."

Killian did as she bid and watched her for a moment as she headed towards the park's waste bins, giving his legs time to awaken after falling asleep from sitting for so long. He placed his hand on the seat to aid him in standing, only to snag his palm on an exposed nail and gashing his flesh.

"Bloody hell!" he grimaced, shaking his injured and throbbing hand, unaware of the droplets of blood he sent flying towards the water's edge.

Or the wavelet his blood sent rushing from the shoreline as a billow of fog misted over the surface of the water.

"Killian?"

The trepidation and terror in Emma's voice pulled his concern from his hand to his wife. All the color had drained from her face. Her lips parted and her eyes were wide as she stood frozen, staring in horror at something he could now hear drifting along the water.

Guarded, he spun to face whatever foe was presenting itself, his torn hand gripping the hilt of his sword. A hiss formed then died on his lips as pain gave way to panic. Slicing through the eerie mist was Charon's boat, the ferry by which souls were transported to the Underworld. This scene had played out for Killian once before. Standing on this very shore with the manifestation of the crocodile by his side, he'd summoned the ferryman with the blood of Rumplestiltskin.

_The blood of a man who'd been to hell and back._

Killian recalled the Darkness' words. _Rumplestiltskin has done what few can claim. He died, and then he returned._

And so had Killian.

"Is that what I think it is?" Emma had apparently snapped out of her her paralysis, and now stood next to him.

"Aye. The ferryman."

"But… how?"

"I'm afraid I opened the portal," he told her, raising his hand to show her the cut.

"No," Emma said, shaking her head. "Regina said she'd sealed it."

Whatever Regina had done, clearly wasn't enough. The proof was making its way towards them, the shrouded figure of Charon hunched over his oar with another hooded figure standing beside him, cutting their way through the veil of mist and fog.

"The veil," Killian exhaled.

"What?"

"The veil between the living and the dead," he reminded her. "It is supposed to be at its thinnest on All Hallow's Eve. Perhaps that is how I was able to open the portal with my blood."

"Who cares?" Emma exasperated. "Who is crossing over and how do we stop them?"

Killian squinted into the darkness, trying in vain to make out the identity of the hooded figure. Just as the familiarity of their presence seeped into his bones, a cold dread freezing his marrow, the figure seemed to evaporate.

"Swan! Get back!"

Killian shoved Emma behind him, knocking her to the ground from the excess force his fear gave him. Viscous tendrils of black, oily mire slithered through the distance between him and the boat, enveloping him in their tentacles of pain and despair. Killian cried out and collapsed to the ground, overcome by the onslaught and only vaguely aware of Emma's screams. He pried his eyes open, desperate to ascertain whether the Darkness had gone after her as well, but he could see nothing past the shell of swarming Dark Ones. His last cognizant thought before being dragged over the precipice and into the oblivion was, _gods above, not Emma. Don't let them take Emma. Not again._

~/~

The smell of stagnation assaulted Killian's sinuses as he groaned and rolled onto his back. The ground beneath him was hard, possibly stone, but not cultivated like those one found in castle halls, more natural and earthen, yet from the staleness of the air filling his lungs, he did not seem to be outside. With great effort, he willed his lids to open under protest and scanned the area around him before his vision even had time to clear.

At first, he was relieved. In those final moments of the Darkness barraging all of his senses before blacking out, he feared he might awaken in the Dark Vault. His relief was short lived, though. With clear eyes he could now make out the cavernous space, it was one he'd been to once before, though he'd had the benefit of being on the other side of the bars then. He may not be in the Dark One's Vault, but he wasn't sure the Dark One's Cell was much of an improvement.

At least it was he and not Emma trapped inside this time.

"About time you woke up."

Killian's heart nearly stopped. That voice. It was the voice of his Swan, but not the Emma he'd been enjoying a quiet moment with only a few… how long had he been out?

Not really wanting to see the proof of what his heart already knew to be true, Killian slowly turned his head towards Swan's voice and swallowed hard. Her golden hair had become a powdery white, the loose tresses now snatched back into a severe bun. The warm, red, oversized coat she'd been wearing was gone, and in its place was the painted on black leather she'd favored after the Darkness had taken up root the first time.

"No." The word escaped him, along with all the air in his lungs, and he staggered to his feet.

"Swan, no," he lamented, his heart clenching at the way her skin sparkled in the firelight of the torch bracketed just outside the cell bars.

"No what?" she rasped. Cold, green eyes pierced him, burning his insides with the ferocity of her anger despite the iciness of her glare.

"No," Killian declared again, shaking his head. This was all wrong. "You can't be…"

"Can't be what?" She stood from where she'd been reclined upon the stone ledge and prowled her way towards him with a slinky sway of her hips. "Can't be the Dark Swan again?" She ran her hand over his chest, trailing her frigid fingers and sharp nails through the coarse hair revealed from the dislodged buttons of his shirt.

Killian stumbled back, shaking his head furiously. "Emma wouldn't give in," he stated to himself. "This isn't real. She resisted the Darkness for weeks. She only gave into it to save me. She wouldn't give in so easily."

"Unless," she purred, her red lips twitching at their corners. "She didn't want you to be the Dark One all on your own."

Killian blanched then looked down at himself. His clothes were different and… he swept a hand through his hair and found it, too, was not as it had been.

"No, I-I don't feel the same as I did… before."

"That's because you haven't fully submitted to the Darkness yet." Emma pressed into him, her body flush with his, her breath hot against his lips. "Don't you remember? How you surrendered yourself to it so quickly last time? The power it gave you?"

"I don't want that power," he growled. "And neither do you." He searched her eyes, his bouncing between hers until he saw the flicker of what he'd been looking for. A sneer twisted at his lips. "You aren't my Emma."

Her brow arched and her face began to morph. A tittering laugh crawled over Killian's skin as the visage of Rumplestiltskin replaced that of the Dark Swan. Killian shoved the demon away from him, but the imp's laugh persisted.

"Where is Emma?" Killian demanded. "Where is she?"

"Not here, dearie." The crocodile perched himself back on the ledge he'd been on, disguised as Emma, and crossed one leg over the other. "Then again, neither am I. Not really."

"What do you mean by that?" Riddles. Always with the riddles. Why could Dark Ones never speak plainly?

"I am merely the manifestation of the Darkness… already residing within you." Killian's stomach turned over at the demon's words. "Though, as I said… or rather, as she said, you haven't fully submitted to the Darkness yet. But you will, dearie."

"Never!"

"If you don't surrender you won't be able to access the fullness of the Darkness' power. You'll need that power in order to escape this cell."

Killian scoffed. _The Dark One lies. "_There is no escape from this cell. It was built to contain you."

"Don't you mean _you_?" Rumple flicked his pointy finger at him and snickered before cajoling, "Fret not. We have learned much since the days of our confinement behind these bars. If you give yourself over to us, as you did before, we can manage our way out. If not…"

"Why must I give in?" Killian challenged. "Emma was powerful in Camelot without fully giving in to the Darkness."

"Because she already had magic as a part of herself," Rumple stated impatiently. "Since you are not magical by nature, you require all that the Darkness can provide in order to wield such power."

"Well, then. I guess that means we're stuck here." Killian lowered himself to the ground and rested his back against the bars, folding his arms over his chest. "I'm not giving in this time, Dark One. Emma will find me, and together we'll find a way to be rid of you."

"That's where you're wrong, dearie." The crocodile hopped down from his perch and crouched before Killian. "Have you not wondered how it was that you came to be trapped here in the cell and not found yourself emerging from the vault?"

It had crossed Killian's mind, and if the Darkness was currently inhabiting him then it knew that all too well. Still, he wasn't going to give the demon the satisfaction of replying.

"It seems," the imp continued, now sitting cross legged in front of Killian, hands gesticulating in its usual ridiculous fashion, "one of the many magic wielders might have foreseen our return and ensured we would become as imprisoned in this realm as we were in the Underworld if we ever gained our freedom from death."

"You were imprisoned in the Underworld?" Killian couldn't help himself from asking. He had no wish to have anything to do with the Darkness, or allow it a foothold, but he couldn't deny his curiosity.

"Of course. Your Rumple might have managed to move on," it said with a disdained roll of the R on its former host's name, "but his wish formed counterpart left us all tethered to the Underworld. Arthur managed to imprison us the moment we arrived, but now, because of you, we are free… almost."

"You'll never be free," Killian vowed between gritted teeth. "I'll see to that."

"You're certainly welcome to try, dearie. Just know this." The Dark One picked himself off the floor and dusted the clingy bits of the cell off his trousers. "The longer you resist the further into madness you'll descend."

Killian brows rose up his forehead and his head cocked to the side. "As if giving into you isn't madness enough."

"Oh, we won't argue with you there, dearie." He was back upon his perch, sneering down at Killian with a maniacally sinister gleam in his eye. "We're all a little mad here, the question is… how quickly and painlessly are you willing to fall into the madness? Denying us will be quite the tortuous descent."

Of that, Killian had no doubt, but he bloody well didn't plan on making it easy for the Darkness this time. He'd fight it every step of the way, no matter the cost to himself. Emma _would _find him, and he wouldn't allow her to free him from the cell until they knew for certain they could banish the Darkness back to the Underworld. He just had to be patient and wait for his Swan.

~/~

Killian carved another tally mark into the craggy wall. It was only a guess at this point, an instinct born from the internal clock the royal navy had programmed into him that had allowed him to wake before the sun without need of an alarm or external signal for so many centuries. With no windows or openings to allow the sun's presence to stream in, he had no way to know for sure how many days had passed since he'd come to be in the cell. The curse of the Darkness did not even give him the estimation sleep would have provided, yet he felt the need to try and mark the time somehow.

Something stirred at the end of the corridor, disrupting the stagnant air that permeated the dungeon and prickling the hairs at the back of his neck. Poised for a fight, Killian rushed to the bars and called out into the darkness.

"Who's there? Reveal yourself!"

Silence echoed back, but Killian could sense something or someone was lingering about. A fury inducing, maniacal giggle sounded from the corner of his cell, snapping Killian's head in its direction.

"Is this one of your tricks, crocodile?" he accused, his lip curling up into a snarl as he glared at the manifestation of Rumplestiltskin perched nonchalantly upon the stone bench.

The demon said nothing, only gave Killian a simpering sort of smirk, so he turned his attention back to the corridor.

Something was out there. He could feel it.

Slowly, he began to pace the length of his cell. His eyes intently watching for any further movement as his hand and hook took turns running along the bars of the enchanted cage. The glinting sound of metal against metal pinged off the rock walls and his gait became more predatory, stalking the unseen intruder with a coiled anticipation as he readied himself to pounce.

A growl worked its way up from the dredges of his being and after long moments his control finally snapped.

"Show yourself!" Killian bellowed with his face pressed between the bars, shaking the very foundations around him with the outburst of his pent up rage. His eyes were wild and his breaths shallow, a madness he'd been desperately trying to keep at bay working its way to the forefront of his psyche.

"There's no one there," the vile imp tittered. "No one is coming to save you. It's just you and me, dearie. Just you and me."

_Just you and me._

He'd said that to Emma in Camelot. Before he knew she was fighting against the demon in her head. Before he knew it _wasn't _just the two of them. It was just two of them now, though. Him and the Darkness. Or a single manifestation of it anyway. The form of Rumplestiltskin hadn't retreated to the recesses of his mind once since making his presence known, and that alone was driving Killian crazy.

_Just you and me._

How much longer would he have to endure the infernal crocodile's company? Where was Emma? Why hadn't she come for him yet? They were supposed to be a team. Even as adversaries they'd been quite the team, and their bond had only gotten stronger over the years. She should have been here by now. Travel between realms had become so much easier in recent years, with portals opening at regular intervals in set locations. Emma and Regina had worked out the necessary magic after Henry had left on his adventure to find his own story, wanting to ensure he'd be able to return to their land regularly. So, why hadn't she bloody well found him yet?

Perhaps something had happened. Some new evil or villain, or a previously vanquished foe who'd returned as the Darkness had? His family might be in danger, unable to mount a search for him.

"You're right. Something must have happened," Rumple agreed with tempered glee. Killian hadn't even been aware he'd said those things aloud. Or had he? "Who knows what other horrors you may have unleashed upon the town when you opened that portal," the crocodile continued. "For all you know they're all dead. Or, perhaps they simply need your help. Surrender and we can go to them. Surrender, and we can save them!"

Killian's knuckles were white from where he was still clutching the bars, his tight grip causing a quivering tingle to run over his hand. He shut his eyes and dragged in a ragged breath, desperate to calm the mania of his mind and hoping to silence the part of his soul that was tempted to side with the Darkness.

_Darkness is a funny thing. It creeps up in you._

"You know it is only a matter of time before you fall. Why fight it?" The Dark One's breath was cold against the back of Killian's neck and a shiver ran down his spine. A scaly arm draped over his shoulders, the imp pressing into him as his words hissed in Killian's ear. "Remember the power. The control. With us at your command, no one would ever be able to stand against you or your family. You'd be able to protect them with certainty. Your saviour would never have to put herself in harm's way and your child would grow up without any threat of danger looming over her precious head. Think of it."

He slithered to Killian's other side, and the reformed pirate's pulse pounded in his ears. His breaths were shallow and quick, matching the erratic beat of his heart, and several times he had to swallow back the pleasant taste salivating along his tongue at the memory of how the magic had made him feel when he'd last been able to wield it.

The Dark One hummed with a knowing tone. "You liked the power. You miss it, don't you? How long has the phantom pains of its absence been burning beneath your skin? Worse than a missing limb, isn't it? Like a part of your soul was ripped from you. We can return it to you. Fill the void and quiet the echoing screams reverberating across the jagged edges of the chasm. Just say the word and all that power can be yours once more."

Killian was nearly hyperventilating, his skin prickled and itching with a need he'd long ago buried deep within himself. He gripped the bar tighter and the wound on his hand broke open. The fresh flow of blood dripped down the bars and covered his fingers in a hot wash of coppery notes that danced along his tongue further watering his mouth. His eyes snapped open and his lips parted, releasing the drool that had collected behind his teeth. Just a taste. He only wanted a taste. The rush of euphoria and exquisite bliss zipping through his bloodstream as he conjured the magic and took command over the ancient darkness, bending it to his will.

Just a taste. All he wanted was a taste.

~/~

Killian sat, curled up against the stone wall, rocking back and forth with his hand and hook over his head. How long had he been here? Days? Weeks? Months? No. It couldn't have been that long. His beard and hair were still relatively short. Or did immortality stunt such growth?

Rumple had cut his hair once. How long had it taken for it to grow back? Killian wished he could remember.

Remember. _Remember who you are._

Those words had come back to him in his moment of weakness. The words he'd said to Emma when she feared she was losing control, when she needed to be reminded of her strength. He'd heard the words in his head when the temptation had almost gotten the better of him, her voice dragging him back from the precipice of surrender.

Since then the Darkness had doubled its efforts, filling his mind with all manner of terrors and forcing him to relive the most horrific moments of his life.

He'd lost count of the number of times Liam had died in his arms. Could feel the sting of centuries old lash strikes upon his back. Faced the knowledge that while they'd been in the Underworld, it had been Rumplestiltskin, not Hades, to send Milah into the River of Lost Souls, her desperate cry as he sent her flying into the current of despair cut through him again and again.

Emma lost to the Darkness, Henry giving his heart to Pan, and his little Hope…

Killian shuddered. He didn't want to think about the things the crocodile had made him experience regarding his daughter. It was bad enough that he could not determine whether she was among the bodies that littered the ground outside the bars.

The Darkness would have him believe they were real, his loved ones slaughtered by some unseen foe ravaging Storybrooke, but Killian refused to accept it. Refused to accept the idea he might have failed them by not giving in to the Darkness. Continued to refuse the demons exertions that he'd be trapped in this infernal cell for all of eternity if he didn't comply.

What would freedom matter now if his family were all well and truly dead?

"I see your point," Rumple mused before flourishing his hands. The bodies disintegrated before Killian's eyes, the ash of their splintering forms carried off by some unfelt wind.

"No!" Killian scrambled forward and reached through the bars, desperately grasping for just a wisp of the floating remains of his loved ones. "What have you done!"

"We've only tried to demonstrate the fate that might befall all those you care about if you persist in your stubbornness," the crocodile chided in a bored tone. "Did you truly believe them all dead?"

Tears streamed down Killian's face, leaving tracks through the grime. He hadn't _wanted _to believe it.

"Their time could very well be running out, though," the demon persisted. "As is yours."

"I'm in no mood for your riddles, demon. Speak plainly."

"You are losing your grip on reality. We told you the madness would take hold. Soon you'll be of no use to us, too mad to wield the power properly. If you don't let us inhabit the deepest parts of yourself then even if your precious saviour comes, it'll be too late."

_Too late._

_She's late._

_Where is she?_

_Sorry I'm late._

Rumple snapped his fingers in Killian's face, jolting him. "You don't look well, dearie."

_Well_

_A wishing well_

_Make a wish and blow out the candle_

_A world created by a wish_

"I wish you'd stop muttering to yourself," the imp snapped.

Had he been saying all of that aloud?

"Yes. You have, and now it is driving _us _mad."

_We're all a little mad here._

_Mad as a hatter._

_Jefferson wasn't mad._

_But he had kidnapped Emma once._

_Once upon a time._

_That's how all fairytales start._

"Might we remind you that you are the villain in your particular fairy tale."

_But you're not a villain anymore_

_Villains don't get happy endings_

_But maybe they get happy beginnings_

_Beginnings_

_It all began on a beanstalk_

The demon sighed and turned away, making its way back to its perch. Halfway across the cell his steps faltered and he seemed to watch something as it crossed his path. Killian could feel the air change around him, a disturbance he'd felt once before that made the fine hairs of his body stand on end. Rumple's eyes narrowed at the far wall of the cavern and Killian started when a scroll of parchment fell from a crevice and landed at his feet. He cast a quick glance at the demon then plucked the scroll from the dusty ground, unfurling it gently with hook and hand.

A single hyphenated word covered the length of the scroll, repeated again and again in a familiar hand.

_Tick-tock._

"Bloody hell," Killian murmured. Perhaps the demon was right. Time was running out.


End file.
